An ultracentrifugal disintegrator of the conventional type includes at least a housing equipped with a system for feeding the material to be comminuted, a motor-driven rotating member (rotor) with blades or pins, an annular sieve positioned around the rotor and a collector for the comminuted material.
In such an apparatus, the comminution of the selected material is carried out through impaction, collision and shearing action. The material arrives into the comminution chamber via the feeder funnel and is caught by the rotor turning at high speed and comminuted into minute particles in less than one second, between the rotor and the annular sieve. The material remains in the comminution chamber only until it reaches the fineness of particles required; under the effect of the centrifugal force, it traverses the annular sieve and reaches the collector.
This type of apparatus is available commercially and is particularly well adapted for grinding quite a variety of inorganic materials (clay, gypsum, limestone), plant materials (cellulose fibers, fodder, wood chips . . . ) or further synthetic materials such as resins and plastics.
In the case of heat sensitive materials being comminuted, whether they be natural or synthetic, this type of apparatus reaches rapidly its limits, and this even more so as the refrigeration modes proposed by the suppliers themselves prove ineffective in numerous cases. As a result, a progressive clogging of the openings of the sieve can occur by the softened or even the molten material, or even worse, the material being comminuted can undergo substantial denaturation. When active substances such as medieaments are processed, this poor control over the temperature conditions prevailing in the comminution chamber can lead to an irreversible alteration of said active substances. In numerous instances investigated, commercial ultracentrifugal disintegrators proved to be unusable.